Laminated glasses with heat reflection function are useful as window glass for automotives and buildings and other purposes for their ability to block the incident heat radiation for enhanced air conditioning performance during summer time as well as for effective energy saving (PTLS 1 to 3).
Laminated glasses with heat reflection function come in two forms: those having a heat reflection film laminated onto glass; and those in which a transparent film laminated with a heat reflection film is sandwiched between glass sheets. The latter type of laminated glass is superior in mass-productivity in that a transparent film laminated with a heat reflection film can be continuously produced and is therefore industrially advantageous.
However, the conventional laminated glass in which a transparent film laminated with a heat reflection film is sandwiched between glass sheets is inferior in durability because when it is subjected to a durability test in the environment of 50° C. and 95% RH, a condition which is required for safety glass for automotives, the laminated glass undergoes color changes and/or the transparent film laminated with a heat reflection film shows clouding occurring from the edge of the laminated glass.
To solve this problem, PTL 3 discloses a laminated glass in which the entire edge of the laminated glass is enclosed by sealing materials.
The laminated glass disclosed in this literature, however, has the problem that while it is applicable to window designed to be affixed to frames, the thickness of the sealing material is small enough to result in failure to attain a moisture exclusion effect in applications where the glass sheets themselves move down and up as in automobile windows.
PTL 4 discloses a heat reflection laminated glass that includes glass having a film-free area around the glass edge, which is obtained by depositing a heat resistant film at a position set back from the glass edge. PTL 5 discloses a laminated glass wherein the edge of a film laminated with a heat reflection film is set back inwardly from the edge of the glass sheet so that a region free of the film laminated with a heat reflection film is provided around the glass edge.
However, the laminated glasses disclosed in these literatures include highly moisture absorbing or permeable interlayer films, such as polyvinyl butyral films, ethylene/vinyl acetate copolymer films or polyurethane films, for manufacture of the laminated glass. Accordingly, these laminated glasses are susceptible to clouding at the peripheral portion due to water penetration from the glass edge in more stringent high-temperature, high-humidity environments or during long-term usage, and therefore, do not necessarily have sufficient durability.
On the other hand, PTL 6 proposes laminated glass that includes an interlayer film made of a modified hydrogenated block copolymer in which an alkoxysilyl group is incorporated into a specific hydrogenated block copolymer. PTL 6 mentions that the interlayer film is superior in heat resistance and low moisture absorption and thus can retain strong adhesion to glass even after exposed to high-temperature, high-humidity environments, and that heat reflection glass can be used.
However, this literature is silent with regard to sealing of a film laminated with a heat reflection film and a method of sealing.